Stainless Steel - Grade 302 (UNS S30200)

Topics Covered

Introduction
Chemical Composition
Mechanical Properties
Other Designations
Manufacturing Process
Applications

Introduction

Grade 302 is a slightly higher carbon version than grade 304. It is widely found in strip and wire forms. It is a standard specification for chromium and chromium-nickel stainless steel sheet, plate, and strip used for pressure vessels and for general applications.

The following datasheet provides an overview of grade 302 stainless steel.

Chemical Composition

The chemical composition of grade 302 stainless steel is outlined in the following table.

Element Content (%)
Chromium, Cr 17-19
Nickel, Ni 8 - 10
Manganese, Mn 2
Silicon, Si 1.00
Carbon, C 0.15
Sulfur, S 0.03
Phosphorous, P 0.045

Mechanical Properties

The mechanical properties of grade 302 (annealed strip) stainless steel are displayed in the following table.

Properties Metric Imperial
Tensile strength 620 MPa 89900 psi
Yield strength (@strain 0.200%) 275 MPa 39900 psi
Elastic modulus 193 GPa 28000 ksi
Poisson's ratio 0.27-0.30 0.27-0.30
Elongation at break (in 50 mm) 55% 55%
Hardness, Brinell (converted from Rockwell B hardness) 147 147
Hardness, Knoop (converted from Rockwell B hardness) 164 164
Hardness, Rockwell B 85 85
Hardness, Vickers (converted from Rockwell B hardness) 147 147

Other Designations

Equivalent materials to grade 302 stainless steel are given below.

AMS 5515 AISI 302 AMS 5516 AMS 5636 AMS 5637
AMS 5688 ASME SA240 ASTM A167 ASTM A240 ASTM A276
ASTM A313 ASTM A314 ASTM A368 ASTM A473 ASTM A478
ASTM A479 ASTM A492 ASTM A493 ASTM A511 ASTM A550
ASTM A554 ASTM A666 FED QQ-S-763 FED QQ-S-766 FED QQ-W-423
ASTM A580 MIL SPEC MIL-S-862 SAE 30302 SAE J230 SAE J405
AMS 5788 DIN 1.4319 MIL S-7720 QQ S763 QQ S766

Manufacturing Process

Grade 302 steel requires slow speeds, and high feeds will aid in overcoming this alloy’s tendency to work harden. It is recommended that chip breakers are used on all tooling due to the occurrence of gummy chips. While welding grade 302, it is recommended that resistance or shielded fusion methods are used. The filler metals to be used are AWS E/ER308 or 312. Post weld annealing is performed when the chromium carbide needs to be dissolved so as to provide maximum resistance to inter-granular attack. Forging is ideally performed at these temperatures - 1149-1260°C (2100-2300°F). It is advisable not to forge below 927°C (1700°F). Forgings should be fully annealed after all operations so as to maintain full corrosion resistance.

Hot working requires uniform heating to 1149°C (2100°F) while cold working helps to increase the hardness of this material. Grade 302 is quite ductile and can be readily drawn, spun and upset. Cold working causes this alloy to gain magnetic properties, and hence post-fabrication annealing is required to recover maximum corrosion resistance and a non-magnetic condition. Annealing is performed between 1010 and 1121°C (1850 and 2050°F) with fast cooling so as to avoid precipitation of chromium carbides.

Applications

Grade 302 stainless steel is widely used in the stamping, spinning and wire forming industry. This alloy is also used to form springs, washers, screens and cables.

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